1. Field of the Invention
This invention relates to facility control, management and communication systems.
2. Background Information
The use of radio frequency (RF) transceivers to establish the location of persons and things is becoming increasingly popular for use in facilities and other areas of interest. One popular approach involves the use of Global Positioning System (GPS) receivers appended to each person and item of interest. The receivers derive a global latitude and longitude position from a series of U.S. government satellites and, when needed, transmit this position to one or more base units with appropriate software to interpret the identity and location of the transmitter. The identity of the transmitter may be uniquely encoded with the position report so that a particular person or item can be correlated with a locational fix. This approach is problematic where reception of satellite signals is attenuated (e.g. indoors or in an area of heavy RF interference). Likewise, this approach requires that expensive and complicated GPS units be attached to each subject for which location-determination is desired.
An alternate approach involves the use of an RF device that transmits to one or more localized, or ground-based (non-satellite) stations. The stations are placed at known locations within a facility, typically so as to avoid excess interference from walls, RF interference and the like. Such implementations generally employ triangulation between a plurality of stations to establish a fairly precise locational fix on the subject. Again, this type of implementation is problematic where interference sources may move about the facility (for example diagnostic equipment in a hospital) or where a number of walls or fixed interference sources may serve to block one or more stations from full reception. Typically, a triangulation-based system is plagued with RF “holes” or RF “distortions” that can only be filled with additional base station units. These units may significantly add to the cost and obtrusiveness of such implementations.
Even where a location-determination system exhibits adequate coverage, it may lack many of the additional functions desired by facilities, such as hospitals. These functions may include determination of encounters between persons and equipment, the ability to access data on proximate individuals and equipment, the logging of medicines administered or supplies used by swiping them with a RFID reader (very close proximity) that is permitted by the proximate positioning of two authorized individuals. Moreover, voice and data communication (RF, WiFi, LAN, VOIP, etc.) in a single system package may be adapted.
More particularly, most currently available location-determination technologies attempt to establish the longest possible range of communication between base units and asset/personnel transponders. In this way, the number of expensive base units may be reduced and they may be used to track a greater number of transponders at a given time. However, this approach often carries the disadvantage of treating the facility's three-dimensional space as a single, large, undifferentiated area within which to locate items and persons. In such a large area, quite precise triangulation and timing of signals from transponders is needed. This, in turn, dictates the use of complex installation and transmission/reception techniques for antenna alignment, particularly in a facility with many walls and/or interference sources. Accuracy remains problematic for such systems due to the inevitable presence of significant RF reflections and wave attenuation as signals attempt to traverse disparate materials in the facility.